Wheel Pulse (Speed) Sensors
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2004 BMW 745i, 2004 BMW 745Li, 2003 BMW 745i, 2003 BMW 745Li, and 2002 BMW 745i. However, it is still accessible from the selected car via links, so may be relevant.
Wheel pulse (speed) sensors are installed at each wheel. Each wheel pulse sensor generates a signal proportional to the speed of a rotating toothed wheel. Wheel pulse sensors relay the signal to the ABS/ASC+T control module, which computes the actual wheel speed. The toothed wheels, which run past the permanently magnetized edge of the speed sensor, are attached to the hub.